Op-Ed

Kinsley: What's the next worst thing?

What injustice do we accept today that will seem outrageous in 20 years?

Same-sex marriage, which seemed at first like a bizarre idea, has become… (Don Emmert / AFP / Getty Images )

Just 16 years after a Democratic president signed the fatuously named Defense of Marriage Act defining marriage as between one man and one woman, the debate over gay marriage is over.

Isn't it? Even though DOMA is still on the books, even though most states that have voted on the issue have voted against gay marriage, all the energy is in the opposite direction. What seemed at first like a bizarre idea has become utterly conventional. By judicial decree interpreting the state constitution, by act of the legislature and someday soon by popular referendum, one state after another is falling. It's already legal across Canada.

Does anybody believe that five years from now it will be harder than it is today for two women or two men to marry? And it's no longer all that hard today. I suspect — don't you? — that even many opponents have given up in their hearts and resigned themselves to taking comfort in one more example of how the country is going to hell.

"What's next?" opponents of gay marriage sometimes have asked. If a man can marry a man, what about a man marrying two men? Or two mixed-gender couples merging into a married foursome? Or — the inevitable reductio ad absurdum — why shouldn't a man marry his German shepherd if he wants to?

No doubt these opponents enjoyed (and deserved, actually) a warm I-told-you-so moment over a recent headline in the New York Times: "Measure Opens Door to Three Parents, or Four." It was about a bill in the California Legislature — California, home of the famous Proposition 8, a successful ballot initiative to outlaw same-sex marriage — to allow for more than two legal parents of a single child.

The bill is about parenting, not about gender. (Even in California, there are only two genders, approximately.) But the bill recognizes the reality of unconventional families: divorced dads who want to keep a close relationship with their kids, lesbian couples who want to adopt each other's children, and so on.

And the opponents of gay marriage are right. Once that initial wall is breached, a lot of this suddenly seems to make perfect sense. Where they're wrong is to think that this is a good argument against gay marriage. Every big societal change carries more change in its wake. And every change is a revolution in perceptions. From the present, you look back 20 years and think, "Why did we find the idea of same-sex marriage so weird?" Twenty years from now, gay marriage will be so common that people might be forgiven for thinking that the Defense of Marriage Act was passed to protect gay marriage.

This is one good reason for reserving some sympathy for those who aren't wholly on board as the train of change comes whistling through: There is something you think today that will seem preposterous and even offensive to your 20-years-from-now self, if you're still around. Some injustice that will seem obvious, although right now we can't see it at all. What will it be? It would be nice to get a heads up.

"Not every disputed institution or practice is destined to be discredited," Princeton philosopher Anthony Appiah wrote a couple of years ago. Looking back, he contrasted abolition (a cause that came "to represent moral common sense") with Prohibition (a cause eventually seen as "quaint or misguided.")

Appiah suggested three signs of a practice that seems harmless today but will seem indefensible tomorrow (or, presumably, vice versa). First, "a particular practice is destined for future condemnation" if the argument against it has been building for a while. "The case against slavery didn't emerge in a blinding moment of moral clarity." Second, the defenders of current practice "invoke tradition, human nature or necessity" rather than morality. Third, the defenders engage in "strategic ignorance." We might say they are in denial about "the evils in which they're complicit."

Today's prohibitionists and abolitionists are already working on some issue that will look completely different to most of us two decades from now than it does today. What is it? Appiah has four nominees:

Prisons. We incarcerate more of our population than any country in the world. Jokes about prison rape are staples of American comedy. In 20 years, we may look back in amazement that people would think this was funny.

Industrial farming. The long-standing discussion of the conditions under which animals are grown for food is turning into a discussion of the morality of using other animals for food at all.

The elderly. Baby boomers already feel guilty about how their parents spend their last years. Just wait until it's the boomers' own turn.

Greenery. Environmental degradation is a debt to our children that parallels the debt to our parents.